Test bench for development of cooling mechanism of the first optical crystal towards SPring-8-II

FRO02
19 Sept 2025, 10:20
20m
The Loop

The Loop

Lund, Sweden
Contributed Oral Presentation Cryogenics Core Technology Developments

Speaker

Haruhiko Ohashi (Japan Synchrotron Radiation Research Institute, RIKEN)

Description

SPring-8 will be upgraded to SPring-8-II, a fourth-generation synchrotron source based on a multi-bend achromat by 2028. Electron beam energy will change from 8 GeV to 6 GeV, substantially decreasing beam emittance. The reduced emittance enables direct observation of the photon source in a beamline design, thus demanding enhanced thermal and mechanical stability in the optics. Currently, most X-ray undulator beamlines at SPring-8 employ standardized double-crystal monochromators with silicon crystals indirectly cooled using liquid nitrogen. Distortion of the crystal directly affects beam quality; hence, optimizing thermal contact between crystal and holder is essential. To accurately replicate beamline operating conditions, we developed a test bench incorporating a crystal holder identical to the actual beamline configuration. In this test bench, the surface deformation of a cryogenically cooled silicon mounted on the holder is precisely measured using a Fizeau interferometer while heating it with an infrared laser, whose penetration depth closely matches that of X-rays. This presentation describes the test bench design and representative results.

Author

Haruhiko Ohashi (Japan Synchrotron Radiation Research Institute, RIKEN)

Co-authors

Hiroshi Yamazaki (Japan Synchrotron Radiation Research Institute, RIKEN) Hikaru Kishimoto (Japan Synchrotron Radiation Research Institute) Yasunori Senba (Japan Synchrotron Radiation Research Institute, RIKEN) Koji Tsubota (Japan Synchrotron Radiation Research Institute)

Presentation materials

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